...... I put a piece of the delrin in non-diluted start san. Over a few days I didn't notice anything but it's still on my desk and the piece of delrin is almost all gone. Pretty much dissolved over a few months.

This bothers me.

I have a mixer installed in each of my cornys but I don't disassemble for every cleaning. I don't rinse after running starsan thru them either. I'm not comfortable with even the slightest chance of any leaching of this plastic into my keg/beer/mouth/body. I use one mixer with 6' of 3/16" beer line and get great pours at 12-14psi.

I've been thinking about other economical options. Has anyone just added a smooth stainless rod to the diptube? I would guess that the diameter, length and smoothness would be the determining factors in how much friction would be introduced. Given the 1/4"/0.250" id, I was thinking a 3/16"/0.1875", 5mm/0.197" or 6mm/0.236" rod might create an equivalent resistance to the mixer. I know nothing of fluid dynamics, so I don't have any idea how this friction equivalency would be calculated using the physical variables.

I plan to purchase rods with my next mcmaster order and test.

Edit: Did a few calculations and a solid 1/8" rod reduces the cross sectional area of a 1/4"ID diptube to 75% of the original. 4mm =>60%, 3/16" =>44%, 5mm =>38%, 6mm =>11% Not sure what that tells me. I don't know how to calculate the resulting flow resistance. I've only been able to find standard resistances for standard beer line diameters but no calculator to actually determine those resistance figures.

Edit: Did a few calculations and a solid 1/8" rod reduces the cross sectional area of a 1/4"ID diptube to 75% of the original. 4mm =>60%, 3/16" =>44%, 5mm =>38%, 6mm =>11% Not sure what that tells me. I don't know how to calculate the resulting flow resistance. I've only been able to find standard resistances for standard beer line diameters but no calculator to actually determine those resistance figures.

More important is the ratio of total surface area (tube and rod) to cross sectional area. This is why 3/16>1/4>3/8 line with respect to frictional coeffecient/length.

Rather than stainless rod/wire, I was thinking of using teflon cord (smooth) as an insert into beer line (accuflex bev-seal, of course). This would allow using 1/4" (or larger) for proper flow (cross section), while gaining improved friction/foot. It would work in 3/16" too, but flow (cross section) would be reduced. Given how good the bev-seal line is, just using more 3/16" line is a simpler option, but shorter hoses would be nice, so would more flow. Have you notice how much better most bar taps flow?

As for solvents- Teflon (PTFE) has no solvents that a homebrewer would ever expose gear to, or any other industrial use either for that matter. I don't think it leaches or off gasses anything either, except at very high temps.

Well, I stumbled upon this thread while trying to figure out way way to lower the amount of foam produced by my new kegerator and thought, amazing! I placed an order for some of these devices and waited until the weekend to install.

Since I'm not using corny kegs, the hose is crimped to the end nut that goes to the sankey so there was no way I was going to be able to slip this in there. I then went to the faucet end of things and was able to remove the hose there since it's fitting was barbed. After all of that, the interior diameter of the hose is too small for one of these!

Bummer... Even at 5-6PSI I get tons of foam, what gives? I've purged the keg and re-filled, and use a very nice dual-regular setup...

Well, I stumbled upon this thread while trying to figure out way way to lower the amount of foam produced by my new kegerator and thought, amazing! I placed an order for some of these devices and waited until the weekend to install.

Since I'm not using corny kegs, the hose is crimped to the end nut that goes to the sankey so there was no way I was going to be able to slip this in there. I then went to the faucet end of things and was able to remove the hose there since it's fitting was barbed. After all of that, the interior diameter of the hose is too small for one of these!

Bummer... Even at 5-6PSI I get tons of foam, what gives? I've purged the keg and re-filled, and use a very nice dual-regular setup...

Try the next size smaller. Beer line has a smaller diameter than the dip tube. That's what I put in my 3 ft picnic tap line that I use to pull the occasional sample from untapped kegs. Work patiently, this was much harder to do as the inserts are easy to break and the fit is tighter in the beer line.